| In recent years,the application of new construction technologies using lighter and more robust materials has promote the construction of an increasing number of tall buildings in large urban areas.As tall buildings are highly sensitive to wind loads,excessive structural responses to wind can easily lead to safety and occupant comfort issues in the design of tall building.At the same time,some tall buildings have circular or polygonal floor plans,with no clearly dominant vibration direction.Tall buildings may not be able to meet safety and comfort requirements under wind loads from various directions.To effectively control the wind-induced vibration responses of tall buildings,passive control systems,represented by water tanks,have been widely applied in practical engineering.Among them,the toroidal liquid column vibration absorber(TLCVA),with its annular configuration and axial symmetry,is particularly suitable for wind-induced vibration control of tall buildings.On one hand,the TLCVA has a larger crosstransition area where the liquid flow is uneven,and the liquid surface is prone to sloshing mode effect,making it difficult to accurately assess the liquid sloshing characteristics in TLCVA by traditional analysis theory.On the other hand,the difficulty in the constructing the large-scale models of the tall building with supplementary TLCVA system in for the wind tunnel testsmakes the real-time hybrid simulation test to be the the most effective way to verify the damping mechanism of the TLCVA system.In addition,optimizing the parameters of the TLCVA system to improve its vibration control performance on structures is also crucial.Therefore,to enhance the investigation on the TLCVA system and reveal its damping mechanism,the comprehensive studies with theoretical analysis,CFD numerical simulation and shaking table test are conducted to investigate the natural frequency and damping of TLCVA,the real-time hybrid test with the electric shaking table is also perfomed to evaluate the wind induced vibration control effect of TLCVA system on tall building.Subsequently,a coupled numerical simulation method by the combind computational fluid dynamics/computational structural dynamics(CFD/CSD)algorithm is proposed,and it is also adopted to compare the wind induced vibration control efficiency of tuned liquid damper(TLD),liquid column vibration absorber(LCVA),and TLCVA systems.Finally,parameter optimization analysis of the vibration control performance of tall building with TLCVA system is presented.The main contents of this dissertation are as follows:(1)Considering the uneven liquid flow in the cross-transition area,the dynamic equation and the analysis model for the natural frequency of TLCVA(elliptical streamline model)are derived by the elliptical streamline method.At the same time,taking into account the liquid sloshing mode effect on the vertical liquid column,the dynamic equation and analysis model for the natural frequency of TLCVA system(liquid soshing mode model)are further proposed.Subsequently,the shaking table tests on the six different structural configurations of TLCVA systems are conducted,and the testd results show that the estimation accuracy in the natural frequency of TLCVA system from the liquid sloshing mode model is superior to those from the traditional model and the elliptical streamline model.The uneven liquid flow in the crosstransition area is not the only reason for the differences of in the natural frequency between the analysis and experimental results,and the effect of liquid sloshing mode cannot be ignored.(2)The analysis of the equivalent damping of TLCVA system is conducted.Based on the assumption that the dymamic characteristic of TLCVA can be represented by the combined effect of multiple LCVAs,the effects of bottom excitation amplitude and effective liquid column length on the head loss of LCVA are first investigated through shaking table tests for LCVA system with or without internal baffles.The results are also compared with those LCVA system with internal orifice plates.On the other hand,the effect of the size of the crosstransition area on the head loss of LCVA system is also numerically evalaued from the CFD simulation results.Based on the head loss of LCVA,an empirical formula for estimation of the head loss for TLCVA is established.The results demonstrate that the numerically evaluted equivalent damping ratio,wave height of free surface,and base shear of TLCVA calculated have a good accuracy in matching with the experimental results.(3)A user interface program for the motion control of the small electric shaking table is developed in Lab VIEW enviormnt.In conjunction with NI Compact RIO hardware and software,a real-time hybrid test platform is constructed by developing Matlab/Simualtion numerical analysis model.Taking the third-generation Benchmark model for wind-induced vibration control study as an example,the effectiveness of the developed real-time hybrid test platform is verified.With the help of this platform,the wind induced vibration control effect of the TLCVA system on tall building is investigated,and the effects of the different excitation directions in wind loading and the wind speed return periods are examined.The compared results indicate that the TLCVA system can effectively be adopted to control the wind-induced response of tall buildings under different excitation directions of wind loading.Although the efficiency of the TLCVA system in controlling the wind-induced response of tall buildings varies slightly with the direction of excitation,the magnitude of variation is very small.(4)Through the integration of numerical CFD simuation on the liquid sloshing with the dynamic analysis on the main structure,a CFD/CSD coupled simulation method is proposed to solve the time-domain dynamic response of the tall building with supplementary damping system under wind loading.The accuracy and reliability of the proposed CFD/CSD coupled simuation method is validated by comparing its reults with those from the real-time hybrid test results for tall building with LCVA and TLCVA system.Subsequently,assuming different types of water tank systems are placed at top of the third-generation wind vibration control benchmark model,the wind-induced vibration response of the tall building with water tanks is conducted.The wind vibration control efficiency of TLD,LCVA,and TLCVA on the main structure is compared.On the mean time the effects of different wind excitation directions,main structural stiffness,main structural damping,and wind speed return period are also studied.The compared results reveal that TLCVA has a higher efficiency in controlling the wind-induced response of tall buildings than TLD and LCVA.TLCVA demonstrates a consistently effective vibration control effect in different wind load excitation directions,whereas TLD and LCVA overall exhibit the most significant damping control effect in the 0° excitation direction but the least effective in the 90° excitation direction.(5)A closed-form analysis solution for estimation of the vibration response of the tall building with TLCVA system under the harmonic loading is proposed,and the optimization on vibration control parameters for the tall building with TLCVA system under harmonic loading is investigated.Compared with traditional iterative method,the proposed closed-form analysis solution obtains good accuracy and reliability,which makes it highly efficient in computation.Using numerical optimization method,the optimal parameters of TLCVA for the optimized control performance(optimal tuning frequency ratio and head loss)are determined.Subsequentlgy,parametric analysis of the vibration control performance of the tall building with TLCVA system is conducted to investigate the effects of structural parameters such as mass ratio,structural damping ratio,tuning frequency ratio,and head loss on the vibration control performance of the tall building with TLCVA system.Finally,a procedure for parameter optimization design onon the wind-induced vibration control of tall building with TLCVA system is proposed in this dissertation.An example for wind-induced displacement control as the optimization goal is presented to demonstrate the efficiency of ths proposed optimization method. |
